Tantallon Castle, a 14th-century fortress in Scotland, stands proudly on a cliff overlooking the Firth of Forth. Built by William Douglas, it's a unique castle with just one massive wall protecting its headland, while the other sides are naturally guarded by cliffs. Despite facing sieges and battles over the centuries, the castle remained in the hands of the Douglas family until it was sold in 1699. Today, this ruined yet majestic castle is under the care of Historic Environment Scotland, offering visitors a glimpse into its storied past and breathtaking views of the surrounding landscape.